If you're in the U.K. you'll know that calling 0800 numbers is free from a landline but when it comes to calling those numbers from your mobile phone, it's a different story. I do recall one carrier I was with a few years ago who didn't charge for calling 0800 numbers, though they changed that eventually. Now though, Three UK are changing things up and making calls to 0800 numbers free.
If you sign up to be a new Pay Monthly customer, calls to 0800, 0808 and 0500 numbers will now be free. They are also making calls to 084x and 087x numbers as little as 5p per minute. That pricing is a lot more reasonable that other carriers right now.
Those aren't the only changes Three are making either. You can now using tethering on all Pay Monthly plans. Previously, you could only tether if you were on The One Plan. All new customers signing up for a pay monthly contract over 24 months can use their data allowance for tethering. One catch is that if you are on an All-You-Can-Eat Plan, you will have a 2GB cap on tethering. Three will now be calling the tethering plan your Personal Hotspot. This doesn't affect you if you're an existing customer.
Good news comes to those looking to unlock their device, though. Three is making their unlocking service free. The service used to cost £15 ($25), so that's a nice treat if you're looking to unlock your Three locked device.